The present invention relates to an ion exchanger.
When a fuel cell is installed in a vehicle or the like, the vehicle includes a cooling circuit through which a refrigerant that cools the fuel cell flows. The cooling circuit limits temperature increases of the battery cell when power is generated.
When a cooling circuit is still new and has just been manufactured, the ions (cations) eluted from the piping of the cooling circuit increase the amount of ions in the refrigerant. The eluted cations in the refrigerant gradually decrease over time. However, when the refrigerant cools the fuel cell, the components in the refrigerant undergo thermal decomposition. This generates ions (anions) and increases the ions in the refrigerant.
When the ions in the refrigerant increase in such a manner, erosion may occur in the metal parts of the cooling circuit. Further, the electric conductivity of the refrigerant may increase and lower the performance of the fuel cell. Thus, the cooling circuit includes an ion exchanger that removes ions from the refrigerant. Japanese Laid-Open Patent Publication Nos. 2002-136968 and 10-174967 disclose examples of ion exchangers known in the art.
In the ion exchangers of the two publications, an ion exchange resin is arranged in a case that includes an inflow hole and an outflow hole. When the refrigerant flows through the inflow hole into the case and passes through the ion exchange resin, the ion exchange resin removes ions from the refrigerant through ion exchange. After the ions are removed, the refrigerant flows out of the case through the outflow hole. The ion exchange resin includes a cation exchange resin that removes cations and an anion exchange resin that removes anions.
In the ion exchanger, the contained amount of ion exchange resin is limited. Thus, when the contained amount of the cation exchange resin is set to obtain the cation removal efficiency that is necessary immediately after the cooling circuit is manufactured, the contained amount of the anion exchange resin decreases. Thus, when the anions in the refrigerant increase as a certain period of time elapses, the anion removal efficiency becomes insufficient. When the contained amount of the anion exchange resin is set to obtain the anion removal efficiency that is necessary when the anions in the refrigerant increase after a certain period of time elapses, the contained amount of the cation exchange resin decreases. Thus, when the amount of eluted cations in the refrigerant increases immediately after the cooling circuit is manufactured, the cation removal efficiency becomes insufficient.